/**
 * rem计算方式：设计图尺寸px / 100 = 实际rem  【例: 100px = 1rem，32px = .32rem】
 */
(function (window) {
  /* 设计图文档宽度 */
  var docWidth = 1920;
  var doc = window.document,
    docEl = doc.documentElement,
    resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize';
  var recalc = (function refreshRem() {
    var clientWidth = docEl.getBoundingClientRect().width;
    if (clientWidth < docWidth) {
      clientWidth = docWidth;
    }
    docEl.style.fontSize = (clientWidth / docWidth) * 100 + 'px';
    return refreshRem;
  })();
  /* 添加倍屏标识，安卓为1 */
  docEl.setAttribute('data-dpr', window.navigator.appVersion.match(/iphone/gi) ? window.devicePixelRatio : 1);
  if (/iP(hone|od|ad)/.test(window.navigator.userAgent)) {
    /* 添加IOS标识 */
    doc.documentElement.classList.add('ios');
    /* IOS8以上给html添加hairline样式，以便特殊处理 */
    if (parseInt(window.navigator.appVersion.match(/OS (\d+)_(\d+)_?(\d+)?/)[1], 10) >= 8) {
      doc.documentElement.classList.add('hairline');
    }
  }
  if (!doc.addEventListener) {
    return;
  }
  window.addEventListener(resizeEvt, recalc, false);
  doc.addEventListener('DOMContentLoaded', recalc, false);
}(window));